Oakland, CA. Tear gas and Flash-Bang grenades used against the people

This video keeps haunting me. The people are completely peaceful. Angry (Rightfully so) but peaceful. They have the right to say what they want to say, and they are threatened (first) to be arrested and then tear-gassed, they got flash-bang grenades thrown at them, and at the end they end up in jail. Is this the famous USA Democracy?

Towards the end of the video (3:18) you can clearly see a protester knocked unconscious. People gather to try to help her and police throw a flash bang grenade into the crowd (3:34). It goes off near her head. Disturbing footage.

Hey, Cops! This crowd is NOT violent, is it clear? Need a drawing?

I mean, guys, throwing a flash-bang directly at the people? What if you actually KILL someone?